The new Spiraea cultivar is a product of a planned breeding program conducted by the inventor, Timothy D. Wood, in Grand Haven, Mich. The objective of the breeding program was to produce new Spiraea varieties of compact and full habit with new and better flower and leaf colors. The breeding program resulting in this new variety began during June of 2007.
The parent varieties are unnamed, unpatented proprietary varieties of Spiraea japonica. Seed was bulk collected from crossing blocks of the parent varieties, and subsequently mutated. A block of 100 mature, flowering unnamed mutated seedlings, selected from crossings of the parent varieties were pretreated with 10 grays of radiation was grown out (designated M1 generation). Seed was collected from ten plants of the mutated seedlings with the best foliage and dark pink flowers. This seed grown out (M2 generation) and selected for superior foliage, flower coverage and flower color. The new variety was identified as a potentially interesting selection in 2009, at a greenhouse in Grand Haven, Mich.
Asexual reproduction of the new cultivar ‘SMSJMLG’ by softwood cuttings was first performed during the Summer of 2009, at commercial greenhouse in Grand Haven, Mich. Subsequent propagation has shown that the unique features of this cultivar are stable and reproduced true to type in successive generations.